MOLLUSCA. 129 



body, regarded as exercising the functions of a prostate 

 gland. Beyond this lies a muscular sac, divided at the top, 

 where it opens by two ducts, but connected at the base. In 

 this sac are numerous white thread-like bodies, terminated 

 by a filament, but unconnected with the sac. In the in- 

 terior they consist of a spiral body, connected at each ex- 

 tremity with a glandular substance. When these bodies 

 are put into water, they twist themselves in various direc- 

 tions, and throw out at one of their extremities an opake 

 fluid. These motions are not excited by placing them in 

 oil or spirit of wine, but they may be exhibited by immers- 

 ing in water those which have been kept for years in spirits. 



These bodies, first observed by Swammerdam, and after- 

 wards by Needham, have been regarded by some as de- 

 monstrating the truth of the vermicular theory of genera- 

 tion ; by others, they have been considered as analogous to 

 the pollen of plants, their tunic is in part soluble in water, 

 and when they are thrown into that fluid, they speed- 

 ily burst, and spread their impregnating contents over the 

 eggs of the female. Although this last conjecture is plau- 

 sible, and countenanced by the circumstance that these ver- 

 micular bodies are only found at the season of reproduction, 

 the subject is still involved in obscurity. Are these bodies 

 produced in the testicle, and only brought to this bag when 

 nearly ready for exclusion ; or, if the product of the bag 

 itself, by what means are they nourished ? 



The male organs terminate in a cylindrical fleshy body 

 termed the Penis. This is hollow within, and ribbed with 

 muscular bands. Near its base it receives one of the ducts 

 of the vermicular sac, continuous with the one from the pros- 

 tate gland, forming its canal, and toward the apex the other 

 duct. It projects but a short way into the cavity of the 



